The invention relates to a method for operating a drivetrain for a motor vehicle, which at least one primary drive axle and at least one secondary drive axle, which are operatively connected with each other via a clutch with an adjustable transmission torque. The invention also relates to a drivetrain for a motor vehicle.
The method serves for operating the drivetrain, to thereby for example drive and in particular accelerate, the motor vehicle. The drivetrain is provided for use in the motor vehicle so that the invention also relates to a motor vehicle with a correspondingly configured drivetrain. The drivetrain has the at least one primary drive axle and the at least one secondary drive axle. These are coupled with each other via the clutch, wherein the transmission torque of the clutch i.e., the torque that is transmitted via the clutch between the primary drive axle and the secondary drive axle can be adjusted.
The primary drive axle is an axle of the drivetrain or the motor vehicle, which in the presence of torque that is directed to drive the motor vehicle is always impinged with this torque or at least a portion thereof. The secondary axle can selectively be impinged with the torque or a portion of the torque. For this purpose the clutch is provided which is situated between the primary drive axle and the secondary drive axle. In a first operating state of the clutch the secondary drive axle is completely decoupled from the primary drive axle. Correspondingly the motor vehicle is only driven by means of the primary drive axle. The transmission of a torque from the primary drive axle to the secondary drive axle does thus not occur. In this case the transmission torque is zero. In a further operating state of the clutch the transmission torque is greater than zero, so that the transmission torque is transmitted from the primary drive axle top the secondary drive axle. In this case also the secondary drive axle contributes to propulsion of the motor vehicle.